1. Field of the Invention
The present invention relates to a magnetic toner for use in a recording method involving the utilization of an electrophotographic method or the like.
2. Description of the Related Art
When the processing speed of an image-forming method based on a jumping method involving the use of a magnetic toner is increased, it becomes difficult to maintain stable image density or image quality. This is caused by the ease of a temperature rise in apparatus or by the insufficient fixing time, both due to the increased processing speed. In addition, the instability is caused by the following situation as well. That is, a rubbing between a cleaning member and the surface of an electrostatic latent image-bearing member intensifies, and hence the stability of a cleaning mechanism reduces and a cleaning failure is apt to occur.
In view of such problems, investigations have been conducted on a material for the magnetic toner and on the control of the state of dispersion of magnetic particles in the magnetic toner for improving developing performance under an environment where the temperature increase is assumed. The investigations include an investigation on an approach to subjecting the surface of the magnetic particles to a hydrophobic treatment to disperse the magnetic particles in the toner particles. Two representative methods are available for the hydrophobic treatment of the magnetic particles. The two methods are a wet treatment performed in water and a dry treatment performed in a vapor phase. The wet treatment has an advantage that the surface of the magnetic particles can be made hydrophobic in a nearly uniform manner, and the dry treatment has an advantage that the treatment is performed with extreme ease. Investigations have been conventionally conducted on the dry treatment by reason of its ease, and techniques concerning various treatment agents have been disclosed (see Japanese Patent Application Laid-open No. 2004-294480).
In addition, a technique to suppress the water vapor adsorption on a magnetic particles through a treatment with a vaporized fluoroalkylsilane and/or a vaporized alkoxysilane has also been disclosed (see Japanese Patent Application Laid-open No. 2000-327948).
However, in the case of the magnetic particles described in each of Japanese Patent Application Laid-open No. 2004-294480 and Japanese Patent Application Laid-open No. 2000-327948, an affinity between an untreated magnetic particles and the treatment agent is insufficient, and hence an untreated portion may remain on the surface of the magnetic particles after the treatment. The untreated portion is apt to adsorb moisture because the portion is hydrophilic. When any such magnetic particles are used to produce toner, the toner shows insufficient development stability in its long-term use under a high-temperature and high-humidity environment.